Heat aging resistant ethylene vinyl acetate copolymer composition and process for its production

ABSTRACT

Heat resistant ethylene vinyl acetate copolymer compositions comprising a blend of ethylene vinyl acetate copolymer, peroxide curable polyacrylate elastomer, and polyamide are described. When crosslinked with a peroxide curative, the ethylene vinyl acetate copolymer compositions exhibit enhanced resistance to heat aging compared to conventional ethylene vinyl acetate elastomer compositions.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from U.S. Patent Application No.61/733,081, filed on Dec. 4, 2012, which is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The present invention is directed to a peroxide curable ethylene vinylacetate copolymer composition, a process for producing a thermosetethylene vinyl acetate elastomer composition having enhanced heat agingperformance, and to articles formed from the thermoset elastomercomposition.

BACKGROUND OF THE INVENTION

Oil resistant ethylene vinyl acetate copolymers are well-known syntheticmaterials formed by copolymerizing ethylene and at least 40 wt % vinylacetate. The ethylene vinyl acetate copolymers may contain onlycopolymerized ethylene units and vinyl acetate units or the copolymersmay comprise additional copolymerized monomers, for example esters ofunsaturated carboxylic acids, such as methyl acrylate or butyl acrylate.The raw polymers, also known as gums or gum rubbers, may be cured byfree radical generators such as peroxides, azides, or by use of highenergy radiation. Examples of commercially available ethylene vinylacetate copolymers include Elvax® resin products from E. I. du Pont deNemours and Company and Levapren® products from Lanxess Corp.

In view of their low cost compared to other oil resistant elastomers,ethylene vinyl acetate copolymers are widely used in the manufacture ofwire and cable jacketing as well as in the production of automotiveparts such as hoses and seals.

Resistance to heat aging is a particularly desirable property in rubberparts that are used in under the hood automotive applications, e.g.hoses, gaskets, and seals. Because such parts may be exposed totemperatures in excess of 160° C. for periods of time, including up toseveral hours on a regular basis, degradation of physical propertiesthrough oxidative embrittlement can occur. In ethylene vinyl acetaterubbers, this often results in a reduction in extensibility and anincrease in hardness and modulus of the rubber article. Such effects aredisclosed for example in published disclosure EP1081188. Methods toenhance hot air or heat aging resistance of ethylene vinyl acetaterubbers have involved attempts to identify more effective antioxidantsystems. However, there is still a need to improve the high temperatureresistance of these copolymers.

It has now been found that it is possible to produce cured ethylenevinyl acetate copolymer compositions of high hardness, strength, andelasticity that exhibit excellent heat aging resistance by dispersingparticles of polyamide in a blend of ethylene vinyl acetate copolymerand a peroxide curable polyacrylate elastomer. The peroxide curablepolyacrylate elastomer comprises copolymerized units of alkyl acrylate,and an amine or acid reactive monomer selected from the group consistingof unsaturated carboxylic acids, anhydrides of unsaturated carboxylicacids, and unsaturated epoxides. The amine or acid reactive monomerallows the polyacrylate elastomer to compatibilize the polyamide and theethylene vinyl acetate copolymer, thereby improving physical propertiessuch as strength and elongation to break. Polyacrylate elastomerscomprising only polymerized units of acrylate monomers generally exhibita poor cure response to peroxide. This is because contiguous polymerizedunits of acrylate monomers may lead to significant chain scission in thepresence of free radicals, so the net increase in crosslink density islow. As defined herein, a peroxide curable acrylate elastomer musteither comprise at least 0.5 mol % of an unsaturated pendant group whichfunctions as a peroxide cure site monomer, or at least 50 mol %copolymerized units of ethylene. Copolymerized ethylene monomer unitsact as spacers between polymerized acrylate monomer units to limitβ-scission.

A number of ethylene vinyl acetate copolymer-polyamide blendcompositions have been disclosed in the prior art. For example, it isknown to add uncured ethylene vinyl acetate copolymers (i.e. gums) topolyamides to form toughened thermoplastic compositions. U.S. Pat. No.4,174,358 exemplifies the use of uncured ethylene vinyl acetatecopolymers at levels up to 20 wt % as toughening additives forpolyamides. A compatibilizer such as a maleic anhydride grafted ethylenevinyl acetate copolymer may also be included in the ethylene vinylacetate copolymer-polyamide blend, as disclosed in J. Polymer Science:Part B: Polymer Physics, Vol. 47, 877-887 (2009). The polyamidecomponent in these compositions comprises the continuous polymer matrixand the uncured ethylene vinyl acetate copolymer is a minor additive.When polyamide comprises the continuous phase in the blend thecomposition generally cannot be processed at temperatures below themelting temperature of the polyamide, or can be processed only withgreat difficulty at such temperatures.

It is also known to form thermoplastic elastomer compositions comprisingethylene vinyl acetate copolymer and polyamide. For example, U.S. Pat.No. 5,948,503 discloses compositions comprising an uncured elasticpolymer, a polyamide in the form of fine fibers, and a polyolefin havinga melting temperature from 80° C. to 250° C. In addition, certainvulcanized compositions are disclosed therein.

Thermoplastic vulcanizates comprising ethylene vinyl acetate copolymerand polyamide, in which the ethylene vinyl acetate copolymer isdynamically crosslinked (i.e., crosslinked under shear mixing to createa dispersion of elastomer particles in a continuous phase of anotherpolymer) are also known. Such compositions are disclosed in EP2098566,and may be improved by the use of a coupling agent such as maleicanhydride grafted ethylene vinyl acetate copolymer as disclosed in U.S.Pat. No. 7,691,943.

U.S. Pat. No. 7,608,216 and U.S. Patent Application Publication2006/0100368 disclose compositions prepared by admixing an uncuredelastomer, for example an ethylene vinyl acetate copolymer, with athermoplastic polymer or another uncured (gum) elastomer. Techniquessuch as fractional curing, partial dynamic vulcanization, or the use ofhigh performance reinforcing fillers are disclosed to increase the greenstrength of the uncured or partially cured compound. The admixedcompositions may be subsequently crosslinked with a curing agent for theelastomer component.

A number of acrylate rubber-polyamide blend compositions have beendisclosed in the prior art. For example, it is known to add uncuredacrylate elastomers (i.e. gums) to polyamides to form toughenedthermoplastic compositions. U.S. Pat. No. 4,174,358 discloses the use ofvarious uncured acrylate elastomers or ethylene based thermoplasticresins comprising up to 95 mole percent ethylene, such asethylene/methyl acrylate/monoethyl maleate/ethylene dimethacrylatetetrapolymers or ionomers of ethylene/methyl acrylate/monoethyl maleateterpolymers, as toughening additives for polyamides. The polyamidecomponent in such compositions comprises the continuous polymer matrixand the uncured acrylate elastomer is a minor additive.

U.S. Pat. No. 5,070,145 discloses thermoplastic blends of polyamideswith ethylene copolymers comprising copolymerized units of dicarboxylicacid anhydrides and optionally alkyl (meth)acrylates. U.S. Pat. No.7,544,757 discloses that blends of ethylene-alkyl acrylate polymers maybe blended at levels up to 30% by weight in polyamide to producetoughened polyamide compositions.

Blends of uncured ethylene acrylic elastomers, polyamides and powderedmetals are disclosed in Japanese Patent 2001-1191387.

U.S. Pat. No. 3,965,055 discloses vulcanizates prepared from a blend ofrubber and 2 wt % to 10 wt % of a crystalline fiber-formingthermoplastic, wherein the thermoplastic is dispersed in the rubbercomponent in particles not greater than 0.5 micron in cross section witha length to diameter ratio greater than 2. The high aspect ratio of thethermoplastic particles enables pressureless curing without voidformation.

Japanese Patent Application Publication H10-251452 discloses adispersion of polyamide particles in a hydrogenated nitrile rubber(HNBR) matrix wherein a compatibilizing polymer that may be an ethylenecopolymer or an acrylate elastomer is also present. The compatibilizingpolymer is ionically crosslinked by metal oxide during mixing with theHNBR and polyamide which prevents the acrylate elastomer from forming acontinuous phase. The HNBR component is then cured with a peroxide orwith sulfur.

U.S. Pat. No. 6,133,375 discloses blends of functionalized rubbers withthermoplastics in which the thermoplastic component is dispersed in therubber phase. Following addition of a curative for the rubber, thecomposition is crosslinked to produce a vulcanized article. Examples offunctionalized rubbers which are disclosed include acrylic rubbers suchas nitrile-butadiene rubber, hydrogenated nitrile-butadiene rubber,epichlorohydrin rubber, and rubbers on which reactive groups have beengrafted, such as carboxylated nitrile-butadiene rubber. Thermoplasticsthat are disclosed include polyetherester block copolymers,polyurethanes, polyamides, polyamide ether or ester block copolymers,and mixtures of polyamides and polyolefins. In the latter case,ethylene-alkyl acrylate copolymers comprising grafted or co-polymerizedmaleic anhydride, glycidyl methacrylate, or (meth)acrylic acid units maybe used to compatibilize the polyamide-polyolefin blend.

U.S. Pat. No. 4,694,042 discloses an elastomeric thermoplastic moldingmaterial containing a coherent phase of polyamide and crosslinkedelastomeric polyacrylate core shell polymers.

U.S. Pat. No. 4,275,180 discloses blends of thermoplastic polymers withacrylate rubbers, the blends being crosslinked or crosslinkable byradiation or peroxide. Fillers may be used in amounts of up to 40% byweight of the composition.

U.S. Patent Application 2006/0004147 discloses blends of elastomers, forexample acrylate elastomers, with thermoplastic polymers such aspolyamides, in which both polymers are coupled and crosslinked by freeradicals, e.g., by electron beam radiation. The compositions maycomprise a continuous phase of thermoplastic with dispersed crosslinkedelastomer particles, or a continuous crosslinked elastomer phase withdispersed crosslinked particles of what was initially thermoplastic.

U.S. Pat. No. 8,142,316 discloses cured blends of elastomers andthermoplastics for use in power transmission belts. The elastomer may bean ethylene acrylic elastomer, and the thermoplastic may be a polyamide.Free radical curatives are disclosed as curing agents.

It is also known to form dynamically cured thermoplastic compositionshaving a polyamide matrix continuous phase and a cured acrylate rubberphase that is present in the form of discrete particles. Thermoplasticelastomeric compositions comprising blends of polyamide and ionicallycrosslinked ethylene acrylic rubber are disclosed in U.S. Pat. No.4,310,638. U.S. Pat. Nos. 5,591,798 and 5,777,033 disclose thermoplasticelastomer compositions comprising a blend of polyamide resins andcovalently-crosslinked acrylate rubber.

Polyacrylate rubber-polyamide blend compositions disclosed in ZeonChemicals L. P., HyTemp® Technical Manual, Rev. 2009-1, p. 46 (2009) aresaid to improve impact strength of plastics. They may also be used toproduce thermoplastic elastomers.

It has now been found that when a dispersion of polyamide particles ispresent in a blend comprising ethylene vinyl acetate copolymer andperoxide curable polyacrylate elastomer, the resultant compositions,when cured by a free radical generator, exhibit enhanced resistance tophysical property loss during heat aging. In addition, such compositionsmaintain excellent tensile strength, modulus, hardness, and elasticproperties such as compression set and elongation at break thatcharacterize conventional ethylene vinyl acetate compositions lackingpolyacrylate elastomer and polyamide.

SUMMARY OF THE INVENTION

Disclosed herein is a blend composition of ethylene vinyl acetatecopolymer, peroxide curable polyacrylate elastomer, and polyamide, saidblend composition consisting essentially of (A) 10 wt % to 98 wt % of anethylene vinyl acetate copolymer component said ethylene copolymercomponent comprising one or more ethylene vinyl acetate copolymers of atleast 40% by weight copolymerized vinyl acetate monomer units; and (B) 1wt % to 50 wt % of a one or more of peroxide curable polyacrylateelastomer component comprising copolymerized units of alkyl acrylate,and at least 0.03 mol % of an amine or acid reactive monomer selectedfrom the group consisting of unsaturated carboxylic acids, anhydrides ofunsaturated carboxylic acids, and unsaturated epoxides; and (C) 1 wt %to 60 wt % of a polyamide component comprising one or more polyamideshaving a melting peak temperature of at least 160° C., wherein saidblend composition has a Mooney viscosity (ML 1+4, 100° C.) determinedaccording to ASTM D1646 of 5 to 200; and wherein each of the weightpercentages of the ethylene vinyl acetate copolymer, polyacrylateelastomer, and polyamide components are based on the combined weight ofthe ethylene vinyl acetate copolymers, polyacrylate elastomers, andpolyamides in the blend composition.

Also disclosed herein is a curable blend composition comprising (A) ablend composition of ethylene vinyl acetate copolymer, peroxide curablepolyacrylate elastomer, and polyamide comprising: (i) 10 wt % to 98 wt %of an ethylene vinyl acetate copolymer component comprising one or moreethylene vinyl acetate copolymers wherein the ethylene vinyl acetatecopolymer comprises at least 40% by weight copolymerized vinyl acetateunits; and (ii) 1 wt % to 50 wt % of one or more of a peroxide curablepolyacrylate elastomer comprising copolymerized units of alkyl acrylate,and at least 0.03 mol % of an amine or acid reactive monomer selectedfrom the group consisting of unsaturated carboxylic acids, anhydrides ofunsaturated carboxylic acids, and unsaturated epoxides; and (iii) 1 wt %to 60 wt % of a polyamide component comprising one or more polyamideshaving a melting peak temperature of at least 160° C., wherein the blendcomposition (A) has a Mooney viscosity (ML 1+4, 100° C.) determinedaccording to ASTM D1646 of 5 to 200; and wherein the weight percentagesof each of the ethylene vinyl acetate copolymer, polyacrylate elastomer,and polyamide components are based on the combined weight of thecomponents of the blend; and

B a curative.

Also disclosed herein is a process for production of a curable blendcomposition comprising ethylene vinyl acetate copolymer, peroxidecurable polyacrylate elastomer, polyamide, and peroxide curativecomprising the steps (A) providing: (i) one or more ethylene vinylacetate copolymers comprising at least 40% by weight vinyl acetatemonomer; (ii) one or more peroxide curable polyacrylate elastomerscomprising copolymerized units of alkyl acrylate, and at least 0.03 mol% of an amine or acid reactive monomer selected from the groupconsisting of unsaturated carboxylic acids, anhydrides of unsaturatedcarboxylic acids, and unsaturated epoxides; and (iii) one or morepolyamides having a melting peak temperature of at least 160° C.; (B)mixing A(i), A(ii), and A(iii) at a temperature above the melting peaktemperatures of the one or more polyamides to disperse the one or morepolyamides within the blend of one or more ethylene vinyl acetatecopolymers and polyacrylate elastomers, such that one or more ethylenevinyl acetate copolymer comprise 10 wt % to 98 wt %, the one or moreperoxide curable polyacylate elastomers comprise 1 wt % to 50 wt %, andthe one or more polyamides comprise 1 wt % to 60 wt % of the blend basedon the total weight of ethylene vinyl acetate copolymers, polyacrylateelastomers, and polyamides present and; (C) cooling the blendcomposition to a temperature below the crystallization peak temperaturesof the one or more polyamides, thereby forming a blend compositionhaving a Mooney viscosity (ML 1+4, 100° C.) of 5 to 200, as determinedaccording to ASTM D1646; and (D) adding a peroxide curative to the blendof part C at a temperature less than 160° C.

A further disclosure herein is a process for preparing a curable blendcomposition comprising polyacrylate elastomer, polyamide, ethylene vinylacetate copolymer, and peroxide curative, said process comprising thesteps: (A) providing (i) one or more peroxide curable polyacrylateelastomers comprising copolymerized units of alkyl acrylate, and atleast 0.03 mol % of an amine or acid reactive monomer selected from thegroup consisting of unsaturated carboxylic acids, anhydrides ofunsaturated carboxylic acids, and unsaturated epoxides; and (ii) one ormore polyamides having a melting peak temperature of at least 160° C.;and (B) mixing the one or more peroxide curable polyacrylate elastomersand one or more polyamides at temperature above the melting peaktemperatures of the one or more polyamides to disperse the one or morepolyamides within the one or more polyacrylate elastomers; (C) coolingthe mixture of part B to a temperature below the peak crystallizationtemperatures of the one or more polyamides to produce an intermediateblend composition having a Mooney viscosity (ML 1+4, 100° C.) less than200 as determined according to ASTM D1646; (D) providing one or moreethylene vinyl acetate copolymers comprising at least 40% by weightvinyl acetate monomer; and (E) mixing the intermediate blend compositionof step (C) with the one or more ethylene vinyl acetate copolymers ofstep (D) to provide the blend composition, wherein said blendcomposition comprises 10 wt % to 98 wt % ethylene vinyl acetatecopolymer, 1 wt % to 50 wt % peroxide curable polyacylate elastomer, and1 wt % to 60 wt % polyamide, each being based on the combined weight ofthe ethylene vinyl acetate copolymers, polyacrylate elastomers, andpolyamides in the blend composition, and wherein said blend compositionhaving a Mooney viscosity (ML 1+4, 100° C.) of 5-200, as determinedaccording to ASTM D1646; and (E) and adding a peroxide curative to theblend of part D at a temperature less than 160° C.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to compositions comprising a blend ofethylene vinyl acetate copolymer, peroxide curable polyacrylateelastomer, and polyamide that, when cured with a free radical sourcesuch as a peroxide curative system, exhibit enhanced resistance tophysical property loss during heat aging. The invention is also directedto compositions consisting essentially of blends of ethylene vinylacetate copolymer, peroxide curable polyacrylate elastomer, andpolyamide, and to curable compositions comprising ethylene vinyl acetatecopolymer, peroxide curable polyacrylate elastomer, polyamide, andperoxide curative. The invention is also directed to curable blendcompositions additionally comprising peroxide curative, and to a processto a process for preparation of cured articles from the heat resistantethylene vinyl acetate copolymer compositions.

Disclosed herein are compositions wherein polyamide particles aredispersed in blends of ethylene vinyl acetate copolymers, (also known asEVM rubbers) and peroxide curable polyacrylate elastomers. The resultantcompositions, when cured, exhibit surprising improvements in physicalproperties. That is, the curing process, which is also commonly referredto as crosslinking or vulcanization, converts the blend of ethylenevinyl acetate copolymer, polyacrylate elastomer, and polyamide to anelastomer composition that exhibits enhanced heat aging resistancecompared to ethylene vinyl acetate elastomer compositions lacking boththe polyacrylate elastomer and polyamide.

Another disclosure herein is a blend composition of ethylene vinylacetate copolymer, peroxide curable polyacrylate elastomer, andpolyamide, said blend composition consisting essentially of: (A) 10 wt %to 98 wt % of an ethylene vinyl acetate copolymer component, saidethylene copolymer component comprising one or more ethylene vinylacetate copolymers of at least 40% by weight copolymerized vinyl acetatemonomer units; and (B) 1 wt % to 50 wt % of a one or more of a peroxidecurable polyacrylate elastomer component comprising copolymerized unitsof alkyl acrylate and at least 0.03 mol % of an amine or acid reactivemonomer selected from the group consisting of unsaturated carboxylicacids, anhydrides of unsaturated carboxylic acids, and unsaturatedepoxides; and (C) 1 wt % to 60 wt % of a polyamide component comprisingone or more polyamides having a melting peak temperature of at least160° C., wherein said blend composition has a Mooney viscosity (ML 1+4,100° C.) determined according to ASTM D1646 of 5 to 200; and whereineach of the weight percentages of the ethylene vinyl acetate copolymer,polyacrylate elastomer, and polyamide components are based on thecombined weight of the ethylene vinyl acetate copolymers, polyacrylateelastomers, and polyamides in the blend composition.

One embodiment of the invention is a curable ethylene vinyl acetatecopolymer blend composition that comprises and a curative, preferably aperoxide curative. The blend composition is characterized by having aMooney viscosity of 5 to 200 as determined in accordance with ASTMD1646, ML 1+4, 100° C.

The blend composition comprises, or in some embodiments consistsessentially of, three polymer components: an ethylene vinyl acetatecopolymer component, a polyacrylate elastomer component, and a polyamidecomponent, and when combined with peroxide curative to form a curablecomposition is referred to herein as a heat resistant ethylene vinylacetate copolymer composition. The ethylene vinyl acetate copolymercomponent of the blend comprises one or more ethylene vinyl acetatecopolymers, each comprising at least 40 wt % vinyl acetate copolymerizedunits.

As used herein, the term “consisting essentially” means with respect tothe blend composition that no more than 30 parts of a polyolefin havinga melting peak temperature greater than 80° C. is present per hundredparts by weight based on the weight of the sum of the ethylene vinylacetate copolymer component and the polyacrylate elastomer component.When more than 30 parts by weight of such high melting point polyolefinis present in the blend composition, the blend composition can bedifficult to process into a curable composition, and if successfullyprocessed, it may have poor elasticity.

The ethylene vinyl acetate copolymers useful in the practice of theinvention described herein comprise copolymerized units of ethylene andvinyl acetate comonomers. Other comonomers may optionally be present,including alkyl esters or alkoxyalkyl esters of propenoic acid, carbonmonoxide, alpha-olefins such as propene, 1-butene, 1-hexene, and thelike, or comonomers that provide epoxide or acid functionality in theethylene vinyl acetate polymer, for example. glycidyl methacrylate,maleic anhydride and its half esters, or (meth)acrylic acid.

The concentration of vinyl acetate comonomer present in these ethylenevinyl acetate copolymers will be at least 40 weight percent, based onthe weight of the ethylene and vinyl acetate comonomer units in thecopolymer. Preferably, the concentration will be at least 45 weightpercent, and more preferably at least 50 weight percent. If theconcentration of vinyl acetate is less than 40 wt %, the ethylene vinylacetate copolymer will lack elastic properties.

Examples of ethylene vinyl acetate copolymers include Elvax® 40L03resin, available from E. I. du Pont de Nemours and Company, Wilmington,Del., USA and Levapren® grades 400 through 900, available from LanxessCorp., Germany.

The ethylene vinyl acetate copolymers that are used to prepare the heatresistant ethylene vinyl acetate copolymer compositions of the inventionare curable gums, i.e. they are substantially uncured rubbers. Bysubstantially uncured is meant that the unblended ethylene vinyl acetatecopolymer has a sufficiently low viscosity to be blended withpolyacrylate elastomer and polyamide. Preferably, the Mooney viscosity(ASTM D1646, ML 1+4 at 100° C.) of the ethylene vinyl acetate copolymeris less than 120, more preferably less than 80 and most preferably lessthan 40.

The polyacrylate elastomers useful in the practice of the inventiondescribed herein are amorphous. That is, the heat of fusion of thepolyacrylate elastomer will generally be less than 4 J/g as measured byASTM D3418-08, preferably less than 2 J/g, and most preferably about 0J/g. The polyacrylate elastomers comprise polymerized units of alkylesters and/or alkoxyalkyl esters of propenoic acid. Examples of suchesters include alkyl acrylates, and alkoxyalkyl acrylates as well asspecies wherein the propenoic acid is substituted with a C1-C10 alkylgroup. Examples of such species include alkyl methacrylates, alkylethacrylates, alkyl propacrylates, and alkyl hexacrylates, alkoxyalkylmethacrylates, alkoxyalkyl ethacryates, alkoxyalkyl propacrylates andalkoxyalkyl hexacrylates. In addition, the alkyl ester groups of thepropenoic acid esters may be substituted with cyano groups or one ormore fluorine atoms. That is, the ester group will be a C1-C12cyanoalkyl group or a C1-C12 fluoroalkyl group. The acrylate polymersmay also comprise copolymerized units of more than one species of thealkyl esters and/or alkoxyalkyl esters, for example two alkyl acrylates.

The alkyl and alkoxyalkyl esters of propenoic acid and substitutedpropenoic acids are preferably C1-C12 alkyl esters of acrylic ormethacrylic acid or C1-C20 alkoxyalkyl esters of acrylic or methacrylicacid. Examples of such esters include methyl acrylate, methylmethacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butylmethacrylate, 2-ethylhexyl acrylate, 2-methoxyethylacrylate,2-ethoxyethylacrylate, 2-(n-propoxy)ethylacrylate,2-(n-butoxy)ethylacylate, 3-methoxypropylacrylate and3-ethoxypropylacrylate. Examples of esters that contain C1-C12cyanoalkyl and fluoroalkyl groups include cyanomethylacrylate,1-cyanoethylacrylate, 2-cyanopropylacrylate, 3-cyanopropylacrylate,4-cyanobutylacrylate, 1,1-dihydroperfluoroethyl methacrylate,1,1-dihydroperfluoroethyl acrylate, 1,1-dihydroperfluoropropylmethacrylate, 1,1-dihydroperfluoropropyl acrylate, and1,1,5-trihydroperfluorohexyl (meth)acrylate, and1,1,5-trihydroperfluorohexyl methacrylate. Preferably, the ester groupwill comprise C1-C8 alkyl groups. More preferably, the ester group willcomprise C1-C4 alkyl groups. Particularly useful alkyl acrylate estersare methyl acrylate, ethyl acrylate and butyl acrylate. A particularlyuseful alkyl methacrylate ester is methyl methacrylate. Minor amounts ofunsaturated acetates such as ethenyl acetate or 3-butenyl acetate may beincorporated into the polyacrylate elastomer without deviating from thescope of this invention. By minor amounts is meant less than 1 wt %,based on the weight of the polyacrylate elastomer.

Esters that comprise comonomer units in the polyacrylate elastomers maybe generally represented by the formula

where R1 is H or C1-C10 alkyl and R2 is C1-C12 alkyl, C1-C20alkoxyalkyl, C1-012 cyanoalkyl, or C1-C12 fluoroalkyl.

In certain embodiments, the polyacrylate elastomers may be polymersderived from copolymerization of more than one acrylate comonomer.Examples of such acrylate polymers include copolymers of methyl acrylateand butyl acrylate; copolymers of methyl acrylate, butyl acrylate andthe monoethyl ester of 1,4-butenedioic acid.

The concentration of propenoic acid ester comonomers that are present inthe polyacrylate elastomer will be at least 50 weight percent, based onthe weight of the polymer. Preferably, the concentration will be atleast 55 weight percent, and more preferably at least 60 weight percent.If the concentration of propenoic acid ester is below 50 wt %, thelikelihood that some crystallinity will be present is high, for examplein acrylate polymers that are ethylene acrylate ester copolymers. Inaddition, a high content of non-polar monomer such as ethylenediminishes compatibility of the polyacrylate polymer with polyamide, andtherefore physical properties of the blend will be decreased.

The polyacrylate elastomers useful in the practice of this invention areperoxide curable, meaning that they comprise either a diene cure sitemonomer at a level of at least 0.5 mol %, or at least 50 mol % ethylene.For example, the polyacrylate may comprise diene cure site monomers toform pendant unsaturation that can form crosslinks in the presence offree radicals, such 1,4-butadiene, 1,6-hexadiene, ethylidene norbornene,and the like. If copolymerized diene cure site monomers are not presentat a level of at least 0.5 mol %, the acrylate polymers must comprise atleast 50 mol % ethylene to confer peroxide curability on thepolyacrylate elastomer.

The polyacrylate elastomers useful in the practice of the inventionfurther comprise copolymerized monomer units selected from the groupconsisting of unsaturated carboxylic acids, anhydrides of unsaturatedcarboxylic acids, unsaturated epoxides, and mixtures of two or morethereof. These monomer units contain chemical groups (e.g., carboxyl andepoxy groups) that react with end groups common in polyamides, e.g.amines and carboxylic acids, and improve the physical properties of theblend.

Unsaturated carboxylic acids include for example, acrylic acid andmethacrylic acid, 1,4-butenedioic acids, citraconic acid, and monoalkylesters of 1,4-butenedioic acids. The 1,4-butenedioic acids may exist incis- or trans-form or both, i.e. maleic acid or fumaric acid, prior topolymerization. Useful copolymerizable cure site monomers also includeanhydrides of unsaturated carboxylic acids, for example, maleicanhydride, citraconic anhydride, and itaconic anhydride. Preferred curesite monomers include maleic acid and any of its half acid esters(monoesters) or diesters, particularly the methyl or ethyl half acidesters (e.g., monoethyl maleate); fumaric acid and any of its half acidesters or diesters, particularly the methyl, ethyl or butyl half acidesters; and monoalkyl and monoarylalkyl esters of itaconic acid. Thepresence of these copolymerized monomers produces polyacrylate elastomercompositions that exhibit good blend compatibility with polyamides.

Examples of useful unsaturated epoxides include for example, glycidyl(meth)acrylate, allyl glycidyl ether, glycidyl vinyl ether, andalicyclic epoxy-containing (meth)acrylates.

Preferably, the acrylate copolymer gum rubber comprises at least 0.03mol % of cure site monomer units bearing the amine or acid reactivegroup, based on the total number of moles of monomer in the copolymer,more preferably at least 0.1 mol %, and most preferably more than 0.2mol %.

In some embodiments, the polyacrylate elastomers useful in the practiceof the invention will also comprise copolymerized units of additionalcomonomers, for example ethylene and other olefins such as propylene,1-butene, 1-hexene, 1-octene, and the like. The olefin will be presentat a concentration of less than 50 wt %, more preferably less than 45 wt%, and most preferably about 40 wt % or less, based on the weight of thepolyacrylate polymer.

The heat resistant ethylene vinyl acetate copolymer compositionsdescribed herein comprise from about 1 wt % to about 60 wt % of one ormore polyamides based on the combined weights of ethylene vinyl acetatecopolymer, polyacrylate elastomer, and polyamide components, wherein thepolyamide component has a melting peak temperature of at least about160° C., more preferably at least 180° C., and most preferably at least200° C., and preferably less than 270° C. as determined in accordancewith ASTM D3418-08. Preferably the polyamide is solid at the curingtemperature of the heat resistant ethylene vinyl acetate copolymercomposition, meaning that the curing temperature is less than themelting peak temperature of the polyamide. While not wishing to be boundby theory, when the polyamide is not solid at the curing temperature,curative readily diffuses into the polyamide, rendering the blenddifficult to cure. Polyamide resins are well known in the art andembrace those semi-crystalline resins having a weight average molecularweight of at least 5,000 and include those compositions commonlyreferred to as nylons. Thus, the polyamide component useful in thepractice of the invention includes polyamides and polyamide resins suchas nylon 6, nylon 7, nylon 6/6, nylon 6/10, nylon 6/12, nylon 11, nylon12, polyamides comprising aromatic monomers, and polyamide blockelastomers such as copoly(amide-ether) or copoly(amide-ester). Theresins may be in any physical form, such as pellets and particles of anyshape or size, including nanoparticles.

The viscosity of the polyamide resins can vary widely while meeting theaims of the present invention. To ensure that the polyamide becomesdispersed within a continuous phase of ethylene vinyl acetate copolymer,it is desirable that the polyamide have an inherent viscosity greaterthan 0.9 dL/g, more preferably greater than 1.1 dL/g, and mostpreferably greater than 1.3 dL/g, as measured in accordance with ASTMD2857-95, using 96% by weight sulfuric acid as a solvent at a testtemperature of 25° C.

In general, as the concentration of the polyamide in the heat resistantethylene vinyl acetate elastomer composition increases, the use of apolyamide of higher inherent viscosity becomes more desirable.

The polyamide resin can be produced by condensation polymerization ofequimolar amounts of a saturated dicarboxylic acid containing from 4 to12 carbon atoms with a diamine, which diamine contains from 4 to 14carbon atoms. The polyamide may also be prepared by a ring openingpolymerization reaction such as nylon 6, or by condensation ofaminocarboxylic acids such as nylon 7 or 11.

Examples of polyamides include polyhexamethylene adipamide (66 nylon),polyhexamethylene azelaamide (69 nylon), polyhexamethylene sebacamide(610 nylon) and polyhexamethylene dodecanoamide (612 nylon), thepolyamide produced by ring opening of lactams, i.e. polycaprolactam,polylauriclactam, poly-11-aminoundecanoic acid, andbis(p-aminocyclohexyl)methanedodecanoamide. It is also possible to usepolyamides prepared by the polymerization of two of the above polymersor terpolymerization of the above polymers or their components, e.g. anadipic acid isophthalic acid hexamethylene diamine elastomer.

Typically, polyamides are condensation products of one or moredicarboxylic acids and one or more diamines, and/or one or moreaminocarboxylic acids, and/or ring-opening polymerization products ofone or more cyclic lactams. Polyamides may be fully aliphatic orsemi-aromatic.

Fully aliphatic polyamides useful in practice of the present inventionare formed from aliphatic and alicyclic monomers such as diamines,dicarboxylic acids, lactams, aminocarboxylic acids, and their reactiveequivalents. A suitable aminocarboxylic acid is 11-aminododecanoic acid.Suitable lactams are caprolactam and laurolactam. In the context of thisinvention, the term “fully aliphatic polyamide” also refers toelastomers derived from two or more such monomers and blends of two ormore fully aliphatic polyamides. Linear, branched, and cyclic monomersmay be used.

Carboxylic acid monomers comprised in the fully aliphatic polyamidesinclude, but are not limited to aliphatic carboxylic acids, such as forexample adipic acid, pimelic acid, suberic acid, azelaic acid,decanedioic acid, dodecanedioic acid, tridecanedioic acid,tetradecanedioic acid, and pentadecanedioic acid. Diamines can be chosenfrom diamines having four or more carbon atoms, including, but notlimited to tetramethylene diamine, hexamethylene diamine, octamethylenediamine, decamethylene diamine, dodecamethylene diamine,2-methylpentamethylene diamine, 2-ethyltetramethylene diamine,2-methyloctamethylenediamine; trimethylhexamethylenediamine,meta-xylylene diamine, and/or mixtures thereof.

Semi-aromatic polyamides are also suitable for use in the presentinvention. Such polyamides are homopolymers, dipolymers, terpolymers orhigher order polymers formed from monomers containing aromatic groups.One or more aromatic carboxylic acids may be terephthalic acid or amixture of terephthalic acid with one or more other carboxylic acids,such as isophthalic acid, phthalic acid, 2-methyl terephthalic acid andnaphthalic acid. In addition, the one or more aromatic carboxylic acidsmay be mixed with one or more aliphatic dicarboxylic acids.Alternatively, an aromatic diamine such as meta-xylylene diamine can beused to provide a semi-aromatic polyamide, an example of which is ahomopolymer comprising meta-xylylene diamine and adipic acid.

Block copoly(amide) elastomers are also suitable for use as thepolyamide component provided the melting peak temperature of thepolyamide block is at least 160° C. If a low softening point materialcomprises the block copoly(amide) elastomer, e.g., a polyether oligomeror a polyalkylene ether, for example, poly(ethylene oxide), then theblock polymer will be a copoly(amide-ether). If a low softening pointmaterial of the block copoly(amide) elastomer comprises an ester, forexample, a polylactone such as polycaprolactone, then the blockelastomer will be a copoly(amide-ester). Any such low softening pointmaterials may be used to form a block copoly(amide) elastomer.Optionally, the lower softening point material of the blockcopoly(amide) elastomer may comprise a mixture, for example, a mixtureof any of the above-mentioned lower softening point materials.Furthermore, said mixtures of lower softening point materials may bepresent in a random or block arrangement, or as mixtures thereof.Preferably, the block copoly(amide) elastomer is a blockcopoly(amide-ester), a block copoly(amide-ether), or mixtures thereof.More preferably, the block copoly(amide) elastomer is at least one blockcopoly(amide-ether) or mixtures thereof. Suitable commercially availablethermoplastic copoly(amide-ethers) include PEBAX® polyether block amidesfrom Elf-Atochem, which includes PEBAX® 4033 and 6333. Most preferably,the polyamide is other than a block copoly(amide-ether) orcopoly(amide-ester). Other polyamides have generally higher melting peaktemperatures and exhibit better hot air aging as compared to polyamideblock copoly(amide-ether) or copoly(amide-ester).

Preferred polyamides are homopolymers or copolymers wherein the termcopolymer refers to polyamides that have two or more amide and/ordiamide molecular repeat units.

The polyamide component may comprise one or more polyamides selectedfrom Group I polyamides having a melting peak temperature of at leastabout 160° C., but less than about 210° C., and comprising an aliphaticor semiaromatic polyamide, for example poly(pentamethylenedecanediamide), poly(pentamethylene dodecanediamide),poly(ε-caprolactam/hexamethylene hexanediamide),poly(ε-caprolactam/hexamethylene decanediamide),poly(12-aminododecanamide), poly(12-aminododecanamide/tetramethyleneterephthalamide), and poly(dodecamethylene dodecanediamide); Group (II)polyamides having a melting peak temperature of at least about 210° C.,and comprising an aliphatic polyamide selected from the group consistingof poly(tetramethylene hexanediamide), poly(ε-caprolactam),poly(hexamethylene hexanediamide), poly(hexamethylene dodecanediamide),and poly(hexamethylene tetradecanediamide); Group (III) polyamideshaving a melting peak temperature of at least about 210° C., andcomprising about 20 to about 35 mole percent semiaromatic repeat unitsderived from monomers selected from one or more of the group consistingof (i) aromatic dicarboxylic acids having 8 to 20 carbon atoms andaliphatic diamines having 4 to 20 carbon atoms; and about 65 to about 80mole percent aliphatic repeat units derived from monomers selected fromone or more of the group consisting of an aliphatic dicarboxylic acidhaving 6 to 20 carbon atoms and said aliphatic diamine having 4 to 20carbon atoms; and a lactam and/or aminocarboxylic acid having 4 to 20carbon atoms; Group (IV) polyamides comprising about 50 to about 95 molepercent semi-aromatic repeat units derived from monomers selected fromone or more of the group consisting of aromatic dicarboxylic acidshaving 8 to 20 carbon atoms and aliphatic diamines having 4 to 20 carbonatoms; and about 5 to about 50 mole percent aliphatic repeat unitsderived from monomers selected from one or more of the group consistingof an aliphatic dicarboxylic acid having 6 to 20 carbon atoms and saidaliphatic diamine having 4 to 20 carbon atoms; and a lactam and/oraminocarboxylic acid having 4 to 20 carbon atoms; Group (V) polyamideshaving a melting peak temperature of at least about 260° C., comprisinggreater than 95 mole percent semi-aromatic repeat units derived frommonomers selected from one or more of the group consisting of aromaticdicarboxylic acids having 8 to 20 carbon atoms and aliphatic diamineshaving 4 to 20 carbon atoms; and less than 5 mole percent aliphaticrepeat units derived from monomers selected from one or more of thegroup consisting of an aliphatic dicarboxylic acid having 6 to 20 carbonatoms and said aliphatic diamine having 4 to 20 carbon atoms; and alactam and/or aminocarboxylic acid having 4 to 20 carbon atoms. Thepolyamide may also be a blend of two or more polyamides.

Preferred polyamides include nylon 6, 6/10, 10/10, 11, 6/12, 12, 6/6,and Group IV polyamides having a melting peak temperature less thanabout 270° C. These polyamides have a melting peak temperaturesufficiently high so as not to limit the scope of applications for theheat resistant ethylene vinyl acetate copolymer compositions, but not sohigh that production of the blends causes significant degradation of theethylene vinyl acetate copolymer or polyacrylate elastomer. Alsopreferred are polyamides formed by ring opening or condensation ofaminocarboxylic acids.

Polyamides suitable for use in the invention are widely commerciallyavailable, for example Zytel® resins, available from E. I. du Pont deNemours and Company, Wilmington, Del., USA, Durethan® resins, availablefrom Lanxess Corp., Germany, and Ultramid® resins available from BASFCorp., USA.

Preferably, the polyamide component of the heat resistant ethylene vinylacetate copolymer compositions is present in the blend composition inthe form of approximately spherical particles, i.e., the aspect ratio ofthe particles is less than 10 to 1. When the aspect ratio exceeds about10 to 1, the viscosity of the blend composition is increased and moldingor extruding the blend composition at a temperature less than themelting peak temperature of the polyamide component becomes difficult.Generally, the size of the polyamide particles is relativelyunimportant, though tensile strength of the cured composition becomesoptimal when most of the particles are about 2 micrometers in diameteror smaller. Such blend compositions can be mixed, molded and/or extrudedusing conventional techniques to produce curable compositions that maybe crosslinked with conventional curative systems to form a wide varietyof elastomer articles.

The blend compositions of the invention comprise, or in some casesconsist essentially of, from about 10 to about 98 weight percent of theethylene vinyl acetate copolymer component described herein, from about1 to about 50 weight percent of the polyacrylate elastomer componentdescribed herein, and from about 1 to about 60 weight percent of thepolyamide component described herein, based on the total weight of theethylene vinyl acetate copolymer, polyacrylate elastomer, and polyamidecomponents. The ethylene vinyl acetate copolymer component may be madeup of one or more than one ethylene vinyl acetate copolymers of the typedescribed herein as being suitable for use in the practice of theinvention. Similarly, the polyacrylate elastomer or polyamide componentmay be made up of one or more than one polyacrylate elastomers orpolyamides of the type described herein as being suitable for use in thepractice of the invention. Preferably, the curable compositions willcomprise from about 30 to about 90 weight percent ethylene vinyl acetatecopolymer component, from about 5 to about 30 weight percentpolyacrylate elastomer, and from about 5 to about 40 weight percentpolyamide component, based on the total weight of the ethylene vinylacetate copolymer and polyamide components. More preferably, the curablecompositions will comprise from about 50 to about 90 weight percentethylene vinyl acetate copolymer component, from about 5 to about 20weight percent of the polyacrylate elastomer component, and form about 5to about 30 weight percent polyamide component based on the total weightof the ethylene vinyl acetate copolymer and polyamide components. Thesepercentages provide a heat resistant ethylene vinyl acetate copolymercomposition such that a cured article made therefrom can, undergo heataging for one week at 190° C. or two weeks at 175° C. and maintain anelongation to break of at least 100%. In addition, the polymer blendsexhibit Mooney viscosities (ML 1+4, 100° C.), as determined according toASTM D1646, of 5-200, preferably 10-150, and most preferably 10-100.

Various blending options can be used, including: (i) mixing polyacrylateelastomers and ethylene vinyl acetate copolymers with molten polyamides,or (ii) mixing polyacrylate elastomers with molten polyamides that aresubsequently cooled to solidify the polyamide and then mixed withethylene vinyl acetate copolymers. These blending options may result ina wide range of blend morphologies, ranging from (i) those whereindiscrete, discontinuous polyamide particles exist within a continuousmatrix of polyacrylate elastomer and ethylene vinyl acetate copolymer,to (ii)) compositions wherein high aspect ratio polyamide “fibers” arepresent, to (iii) compositions that comprise co-continuous structures,to (iv) compositions comprising discrete domains of polyacrylateelastomer and ethylene vinyl acetate copolymer within a continuous phaseof polyamide. Most of these compositions have morphologies that areunsuitable for use in the present invention, because the blends havevery high Mooney viscosities, i.e. Mooney viscosity ML 1+4, 100° C. ofgreater than about 200, or exhibit such poor processability attemperatures less than the melting peak temperature of the polyamidethat the Mooney viscosity cannot be measured. A Mooney viscosity greaterthan 200, or the inability to measure Mooney viscosity, indicates thatthe polyamide comprises a continuous or a high aspect ratio fibrousphase in the blend. Such blends exhibit poor processability forextrusion or molding, and poor elastic properties after curing if acured article can successfully be formed. A Mooney viscosity less than200, preferably less than 150, and most preferably less than 100, isconfirmatory of a blend morphology wherein the polyamide comprises adiscontinuous phase that does not have a high aspect ratio.

With respect to the polyamide of the present invention, by“discontinuous” is meant that the polyamide is present in the blendcompositions of the invention as dispersed particles or domainssurrounded by ethylene vinyl acetate copolymer and polyacrylateelastomer. By “high aspect ratio” is meant that the ratio of the largestto smallest dimensions of a typical polyamide domain in the blend isgreater than about 10. In general, the polyamide domains in the heatresistant ethylene vinyl acetate copolymer compositions of the inventionwill preferably be completely isolated from each other within thecontinuous ethylene vinyl acetate copolymer and polyacrylate elastomermatrix, and be approximately spherical. However, in certain instances asmall percentage, less than about 5%, of localized sites in the blendcomposition may exist wherein the polyamide domains are aggregated orconnected to each other, or have an aspect ratio greater than about 10.After cooling, the polyamide domains no longer flow and the morphologyof the polyamide component remains unchanged during further mixingprocesses at temperatures less than the melting peak temperature of thepolyamide.

A preferred method of producing the blend compositions involves asequential blending process. A peroxide curable polyacrylate elastomercomponent comprising copolymerized units of alkyl acrylate and at least0.03 mol % of an amine or acid reactive monomer selected from the groupconsisting of unsaturated carboxylic acids, anhydrides of unsaturatedcarboxylic acids, and unsaturated epoxides and a polyamide component arefirst mixed at a temperature above the melting peak temperature of thepolyamide, to disperse the polyamide in a continuous phase ofpolyacrylate elastomer. The polyacrylate elastomer-polyamide blend isthen cooled and blended with ethylene vinyl acetate copolymer at atemperature less than the melting peak temperature of the polyamide toform a blend composition comprising 10-98 wt % ethylene vinyl acetate,1-50 wt % polyacrylate, and 1-60 wt % polyamide. Because the polyamidemorphology is determined by the initial melt mixing step withpolyacrylate elastomer, to ensure the polyamide does not comprise thecontinuous phase of the polyacrylate elastomer-polyamide blend, theMooney viscosity (ML 1+4, 100° C.) of this blend must be measurable andless than 200, preferably less than 150, most preferably less than 100.Sequential blending as described eliminates the need to expose therelatively thermally unstable ethylene vinyl acetate copolymer to thehigh temperatures needed for melt mixing with polyamide. In addition,the compatibilization reaction between polyamide and acid or aminereactive sites on the polyacrylate elastomer is favored when ethylenevinyl acetate copolymer is substantially absent during the melt mixingprocess.

Alternatively, one is able to prepare a blend composition, as disclosedherein by the following process. The process starts with providing oneor more ethylene vinyl acetate copolymers comprising at least 40% byweight vinyl acetate monomer; one or more peroxide curable polyacrylateelastomers comprising copolymerized units of alkyl acrylate, and atleast 0.03 mol % of an amine or acid reactive monomer selected from thegroup consisting of unsaturated carboxylic acids, anhydrides ofunsaturated carboxylic acids, and unsaturated epoxides; and one or morepolyamides having a melting peak temperature of at least 160° C. Theprocess then requires mixing the components at a temperature above themelting peak temperature(s) of the one or more polyamides to dispersethe one or more polyamides within the one or more ethylene vinyl acetatecopolymers and polyacrylate elastomers, such that one or more ethylenevinyl acetate copolymer comprise from about 10 wt % to about 98 wt %,the one or more peroxide curable polyacylate elastomers comprise fromabout 1 wt % to about 50 wt %, and the one or more polyamides comprisefrom about 1 wt % to about 60 wt % of the blend based on the totalweight of ethylene vinyl acetate copolymers, polyacrylate elastomers,and polyamides present. After mixing these, the mixture is cooled to atemperature below the crystallization peak temperatures of the one ormore polyamides, thereby forming a blend composition having a Mooneyviscosity (ML 1+4, 100° C.) of 5 to 200, as determined according to ASTMD1646.

A heat resistant ethylene vinyl acetate copolymer composition may beformed by a process that includes mixing a peroxide curative into ablend composition comprising 10-98 wt % ethylene vinyl acetate, 1-50 wt% polyacrylate, and 1-60 wt % polyamide having a Mooney viscosity (ML1+4, 100° C.) of 5 to 200, as determined according to ASTM D1646, at atemperature below the melting peak temperature of the one or morepolyamides.

The heat resistant ethylene vinyl acetate copolymer compositions mayonly be formed by mixing the polyamide component into the polyacrylateelastomer component and optionally the ethylene vinyl acetate componentat temperatures above the melting peak temperature of the polyamide,under conditions that do not produce a dynamic cure of the polyacrylateelastomer or the ethylene vinyl acetate copolymer, followed by coolingthe thus-produced polymer blend. That is, the curative, generally aperoxide curative, will not be present when the polyamide component,polyacrylate elastomer component, and optionally the ethylene vinylacetate copolymer component are being mixed. This is because the mixingtemperature specified (above the melting peak temperature of the one ormore polyamides) is above that at which crosslinking and/or gelling ofthe polyacrylate elastomer or ethylene vinyl acetate copolymer willoccur in the presence of peroxide. Gelling or crosslinking of thepolyacrylate elastomer or ethylene vinyl acetate copolymer during mixingwith molten polyamide forces the polyamide to become the continuousphase in the blend, so that after the blend composition has cooled andthe polyamide has solidified, the blend composition becomes difficult orimpossible to further process at a temperature less than the meltingpeak temperature of the polyamide component. In particular, a blendcomposition with a continuous polyamide phase may exhibit a Mooneyviscosity (ML 1+4, 100° C.) greater than 200, or it may exhibit flowbehavior such that the Mooney viscosity cannot be measured. Inability tomeasure a Mooney viscosity of the blend composition occurs eitherbecause the blend cannot be formed into the Mooney test specimen byconventional rubber processing techniques at a temperature less than themelting peak temperature of the polyamide, or because the test specimencrumbles during the Mooney test.

Cooling of the blend composition formed by mixing the polyacrylateelastomer component, polyamide component, and optionally the ethylenevinyl acetate component serves to crystallize the polyamide domains sothat the polyamide becomes solid and therefore cannot coalesce to form acontinuous phase upon subsequent mixing, e.g., when mixed with anperoxide curative to form a curable composition. The resulting mixturecan be an intermediate blend composition in the case where one or moreethylene vinyl acetate copolymers are added, for example if ethylenevinyl acetate copolymer was not present during the mixing of thepolyacrylate elastomer and polyamide, or if additional ethylene vinylacetate copolymers are added to a blend of polyacrylate elastomer,ethylene vinyl acetate copolymer, and polyamide. Preferably, theethylene vinyl acetate copolymer is mixed with the intermediate blend ata temperature less than the melting peak temperature of the polyamide.The temperature below which the blend must be cooled can be determinedby measuring the crystallization peak temperature according to ASTMD3418-08. The blends of ethylene vinyl acetate copolymer, polyacrylateelastomer, and polyamide may exhibit multiple crystallization peaktemperatures. In such cases, the lowest crystallization peak temperatureis taken as the temperature below which the blend must be cooled tofully solidify the polyamide component. Generally, the blend is cooledto 40° C. or less, which is sufficient to solidify the polyamides usefulin the practice of the present invention.

The curable compositions that are heat resistant ethylene vinyl acetatecopolymer compositions described herein also comprise a peroxidecurative. By “curable” is meant that the increase in torque measured inaccordance with ASTM D5289-07a using an MDR 2000 from Alpha Technologiesoperating at 0.5° arc and at test conditions of 177° C. for 24 minutesis at least 2.5 dN-m. More preferably the torque increase is at least 4dN-m, and most preferably at least 5.5 dN-m. The increase in torque isthe difference MH-ML, where ML refers to the minimum torque valuemeasured and MH refers to the maximum torque value attained after themeasurement of ML. Suitable peroxide curatives, also known as peroxidecuring systems, comprise a peroxide and optionally a coagent. Examplesof peroxides and coagents include curative systems as generally known inthe art, including those described herein, operative at the temperatureemployed during vulcanization. For example, useful organic peroxides arethose that decompose rapidly within the temperature range of 150° C. to250° C. These include, for example, dicumyl peroxide,2,5-bis(t-butylperoxy)-2,5-dimethylhexane, andα′,α′-bis(t-butylperoxy)-diisopropylbenzene (available from Arkema Inc.under the tradename Vul-Cup® peroxide). In a typical curable compositionthe peroxide is present in amounts of from about 0.5 to 5 parts phr(parts per hundred parts rubber, i.e. parts per hundred parts of the sumof the ethylene vinyl acetate copolymers and polyacrylate elastomerspresent). The peroxide may be adsorbed on an inert carrier such ascalcium carbonate, carbon black or kieselguhr; however, the weight ofthe carrier is not included in the above range. Generally, an optionalcoagent will be present to increase the state of cure of the finishedpart. The coagent can be for example, N,N′-(m-phenylene)dimaleimide,trimethylolpropane trimethylacrylate, tetraallyloxyethane, triallylcyanurate, tetramethylene diacrylate, or polyethylene oxide glycoldimethacrylate. A preferred coagent is N,N′-(m-phenylene)dimaleimide,available from E. I. du Pont de Nemours and Company as HVA-2. The amountof the coagent used is generally about 0 to 5 parts by weight per 100parts (phr) of the sum of the ethylene vinyl acetate copolymer andpolyacrylate elastomer, preferably about 1 to 5 parts phr. The coagentsusually contain multiple unsaturated groups such as allyl groups oracrylic ester groups.

The addition of curative to the blend composition will desirably takeplace at a temperature below the decomposition temperature of theperoxide and below the temperature at which the crosslinking reactionoccurs. Generally, the addition will take place at a temperature below160° C., preferably below 140° C., and most preferably at a temperatureno greater than 120° C. The addition of the curative may take placesimultaneously with the addition of optional processing ingredients,such as colorants, conventional carbon black or mineral reinforcingagents, antioxidants, processing aids, fillers and plasticizers, or itmay be an operation separate from addition of the other ingredients. Theaddition may be conducted on a two-roll rubber mill or by using internalmixers suitable for compounding gum rubber compositions, includingBanbury® internal mixers, Haake Rheocord® mixers, Brabender Plastograph®mixers, Farrel Continuous Mixers, or single and twin screw extruders.

After addition of the curatives and other optional ingredients such asfillers, plasticizers, pigments, antioxidants, process aids, etc., tothe blend composition, the resulting heat resistant ethylene vinylacetate copolymer composition desirably exhibits a strong (meaningfavorable) cure response as determined in accordance with ASTM D5289-07ausing an MDR 2000 from Alpha Technologies, Ohio, USA operating at 0.5°arc and at test conditions of 177° C. for 24 minutes.

In another embodiment, the invention is directed to a curablecomposition that is a heat resistant ethylene vinyl acetate copolymercomposition comprising ethylene vinyl acetate copolymer, polyacrylate,polyamide, and a peroxide curative. Said curable composition exhibits anincrease in torque of at least 2.5 dN-m, preferably at least 4.0 dN-m,and most preferably at least 5.5 dN-m, as determined in accordance withASTM D5289-07a using an MDR 2000 from Alpha Technologies operating at0.5° arc and at test conditions of 177° C. for 24 minutes.

To achieve optimal heat aging resistance, an antioxidant may be added tothe curable ethylene vinyl acetate copolymer composition prior tocuring. Useful antioxidants include, but are not limited to, arylamines, phenolics, imidazoles, and phosphites. Thus, in someembodiments, the antioxidant will be a phosphorus ester antioxidant, ahindered phenolic antioxidant, an amine antioxidant, or a mixture of twoor more of these compounds. The proportion of the antioxidant compoundin the composition is typically 0.1 to 5 phr, preferably about 0.5 to2.5 phr. The weight ratio of the phenolic or amine antioxidant to thephosphorus compound in the mixtures is about 0.5 to 3, and preferablythe ratio is about 1.

Examples of aryl amines that may be useful antioxidants include4,4′-bis(α,α-dimethylbenzyl)diphenylamine, diphenylamine and alkylateddiphenylamines, 4-aminodiphenyl amine, andN-phenyl-N′-(p-toluenesulfonyl)-p-phenylenediamine. Examples of phenolicantioxidants include 4,4′-butylenebis(6-t-butyl-m-cresol),1,3,5-trimethyl-2,4,6-tris-(3,5-di-t-butyl-4-hydroxybenzyl)benzene, and4,4′-thiobis-(3-methyl-6-t-butylphenol). Examples of phosphiteantioxidants include triphenylphosphite,bis(2,4-di-t-butylphenyl)pentraerythritol diphosphite, andtris(2,4-ditert-butylphenyl)phosphite. Examples of imidazoleantioxidants include 2-mercaptomethylbenzimidazole,2-mercaptobenzimidazole, and zinc 4- and-5-methyl-2-mercapto-benzimidazole. Combinations of antioxidants may beused, generally at levels between 0.1 and 5 phr based on 100 parts ofthe ethylene vinyl acetate copolymer in the compound.

Suitable hindered phenolic antioxidants can be, for example4,4′-butylidenebis(6-t-butyl-m-cresol),1,3,5-trimethyl-2,4,6-tris-(3,5-di-t butyl-4-hydroxybenzyl)benzene,2,6-di-t-butyl-α-dimethylamino-p-cresol and4,4′-thiobis-(3-methyl-6-t-butylphenol).

Antioxidants comprising the salt of a strong base and a weak acid,optionally combined with a carbodiimide, as disclosed in EP1081188, mayalso be used in the heat resistant ethylene vinyl acetate copolymercompositions.

Preferred antioxidant compositions contain tri(mixed mono- anddinonylphenyl) phosphate mixed with either4,4′-butylidenebis(6-t-butyl-m cresol) or4,4′-bis(α,α-dimethylbenzyl)diphenylamine. Preferred antioxidantcompositions contain 4,4′-bis(α,α-dimethylbenzyl)diphenylamine(available commercially as Naugard® 445 from Chemtura Corp.) or4-aminodiphenyl amine. Antioxidants may be added while the ethylenevinyl acetate copolymer is melt mixed with the polyamide, or after theblend has cooled.

In other embodiments, the heat resistant ethylene vinyl acetatecopolymer compositions of the invention may be blended with anotherpolymer, e.g. an elastomer, to dilute the polyamide content of theinventive composition by any mixing process, either above or below themelting peak temperature peak of the polyamide, providing the presenceof the additional polymer does not increase the Mooney viscosity (ML1+4, 100° C.) of the resulting composition to above 200. The polymerused for the blending process may be an ethylene vinyl acetate copolymeror polyacrylate elastomer, and may further comprise fillers, curatives,or other ingredients. Preferably, such dilution occurs at a temperaturebelow that of the melting peak temperature of the polyamide, and if acurative is present, below the temperature needed to initiate curing.

In addition, the heat resistant ethylene vinyl acetate copolymercompositions may optionally comprise additional components includingfillers, including but limited to carbon black, mineral fillers, scorchretarders, ignition resistant fillers and additives, plasticizers,process aids, waxes, pigments, and colorants. Such optional componentswill generally be present in amounts of from about 0.1 phr to about 200phr, based on the weight of the sum of the ethylene vinyl acetatecopolymer and polyacrylate elastomer. The addition of such optionalcomponents may take place during preparation of the polymer blend or atthe time of mixing of curative into the composition.

Curing or crosslinking (also referred to as vulcanization) of thecurable compositions of the invention typically involves exposing theheat resistant ethylene vinyl acetate copolymer composition to elevatedtemperature and elevated pressure for a time sufficient to crosslink theethylene vinyl acetate copolymer and polyacrylate elastomer. Suchoperations generally are conducted by placing the curable heat resistantethylene vinyl acetate composition into a mold that is heated in a press(often referred to as press-curing). Alternatively, the curablecompositions may be extruded into various shapes. Such extruded shapesor parts are often cured in a pressurized autoclave. After the presscure or autoclave cycle is completed, this initial cure may be followedby an optional post-cure heating cycle at ambient pressure to furthercure the heat resistant ethylene vinyl acetate copolymer composition.For example, the vulcanizate may be formed and cured using conventionalpress cure procedures at about 160° C. to about 220° C. for about 1 to60 minutes. Post-cure heating may be conducted at about 160° C. to about200° C. for one to several hours. Once crosslinked, the compositionsdescribed herein are not thermoplastic, but thermoset. Suitable cureconditions will depend on the particular curable compound formulationand are known to those of skill in the art.

The vulcanizates prepared from the heat resistant ethylene vinyl acetatecopolymer compositions described herein exhibit unusually goodresistance to embrittlement during heat aging, as evidenced by retentionof tensile elongation at break following heat aging at 190° C. for oneweek or two weeks at 175° C. and a reduction in the increase in Shore Ahardness as a result of heat aging. For example, replacement of onequarter of the ethylene vinyl acetate copolymer in a curable compound bya blend of polyacylate elastomer and polyamide can provide over fivetimes greater elongation at break after one week heat aging at 190° C.,and over five times less change in Shore A hardness. This degree ofimprovement is unusual. Furthermore, these advantages in heat aging aregained with no sacrifice in compression set resistance.

Heat resistant ethylene vinyl acetate copolymer compositions prepared bythe processes described herein can be used in a wide variety ofindustrial applications, for production of articles including wire andcable jacketing, spark plug boots, hoses, belts, miscellaneous moldedboots, molded or extruded tubing or hose, molded boots, belts, grommets,seals and gaskets, vibration dampeners, weather stripping, seals andgaskets. Hose applications include turbocharger hoses, transmission oilcooler hoses, power steering hoses, air conditioning hoses, air ducts,fuel line covers, and vent hoses.

Examples of seals include engine head cover gaskets, oil pan gaskets,oil seals, lip seal packings, O-rings, transmission seal gaskets, sealgaskets for a crankshaft or a camshaft, valve stem seals, power steeringseals, and belt cover seals.

Automotive tubing applications include axle vent tubing, PCV tubing andother emission control parts. The vulcanizates are also useful formanufacture of crankshaft torsional dampers where high damping over abroad temperature range is needed under high compressive and shearstrains. The vulcanizates also can be used to prepare noise managementparts such as grommets.

The invention is further illustrated by the following examples whereinall parts are by weight unless otherwise indicated.

EXAMPLES Materials Ethylene Vinyl Acetate Copolymer (EVA)

EVA1 Copolymer of ethylene and 50 wt % vinyl acetate, Mooney viscosity(ML 1+4 at 100° C.) of 25, available from Lanxess Corp. as Levapren® 500resin.

EVA2 Copolymer of ethylene and 45 wt % vinyl acetate, Mooney Viscosity(ML1+4 at 100° C.) of 19, available from Lanxess Corp. as Levapren® 450resin.

Polyacrylate Elastomer

AE1 Amorphous copolymer of methyl acrylate, ethylene and monoethylmaleate comprising 55 wt % (about 29 mole %) copolymerized methylacrylate units, 43 wt % coplymerized ethylene units (about 70 mol %),and approximately 2 wt %(about 0.6 mol %) copolymerized units ofmonoethyl maleate; Mooney viscosity (ML 1+4) at 100° C. of 33.

Polyamide

P1 Polyamide 6, inherent viscosity 1.450 dL/g, melting peak temperature220° C., available from BASF as Ultramid® B40.

P2 Polyamide 6/6, melting peak temperature 262° C., available from E.I.duPont de Nemours as Zytel® 42A.

Other Ingredients

Peroxide: mixture of the para and meta isomers of anα,α′-bis(tert-butylperoxy)-diisopropylbenzene, 40% peroxide activeingredient on kaolin clay carrier, Vul-Cup® 40KE, available from ArkemaInc.Coagent: N,N′-(m-phenylene)dimaleimide, HVA-2, available from DuPont.Carbon black: N550 grade, Sterling® SO carbon black, available fromCabot Corp.Antioxidant (AO): Naugard® 445 antioxidant, available from ChemturaCorp.

Test Methods

Mooney viscosity: ASTM D1646, ML 1+4, 100° C.Cure response: Measured per ASTM D5289-07a using an MDR 2000 from AlphaTechnologies operating at 0.5° arc. Test conditions of 177° C. for 24minutes. ML refers to the minimum torque value measured during the test,while MH refers to the maximum torque value attained after ML.Compression set: ISO 815-1:2008, 25% compression, using type B moldedbuttons prepared using press cure conditions of 175° C. for 10 minutes.Time and temperature of the test conditions as specified. Data reportedare the median values of 3 specimens.Tensile properties: ASTM D412-06, die C. Samples cut from 1.5 to 2.5 mmthick molded plaques press cured at 175° C. for 10 minutes and optionalpost cure of 30 minutes at 175° C. as noted followed by aging for 24hours at ambient conditions of 23° C. and 50% relative humidity. Datareported are the median value of 3 specimens. The rupture properties oftensile strength and elongation are indicated as Tb and Eb, (tensile atbreak and elongation at break, respectively). Test temperature is 23°C.+2° C. Shore A hardness: measured using 6 mm thick samples composed of2 mm thick plies, cured as described for tensile properties, aged for 24hours at ambient conditions of 23° C. and 50% relative humidity, perASTM D2240-05 test method, using a type 2 operating stand. The medianvalue of 5 readings is reported.Heat aging: Tensile specimens, prepared as described above are hung in ahot air oven for the specified time and temperature. The specimens areconditioned at ambient conditions of 23° C. and 50% RH for at least 24hours before tensile properties are measured.Inherent viscosity of polyamides: Measured in accordance with ASTMD2857-95, using 96% by weight sulfuric acid as a solvent at a testtemperature of 25° C. Samples were dried for 12 hours in a vacuum ovenat 80° C. prior to testing.Melting peak temperature: Measured in accordance with ASTM D3418-08.

Example 1

Blend B1, comprising polyacrylate elastomer and polyamide, was producedas follows. Polyamide P1 was metered by weight loss feeder into thefirst barrel section of a 43 mm Berstorff® co-rotating twin screwextruder with twelve barrel sections, operating at a screw speed of 250rpm. At the same time, polyacrylate elastomer AE1 was metered into thefourth section of the extruder via a specially configured extruder and amelt pump for accurate feed rates. Melt temperature of the blend reachedabout 280° C. After exiting the twelfth barrel section, the resultantblend was pelletized and cooled to 25° C. before further processing.Composition and properties of blend B1 are shown in Table 1.Transmission electron micrographs of blend B1 indicate that thepolyacrylate elastomer is the continuous phase in the blend, and thepolyamide is dispersed in roughly spherical domains of approximately 0.5to 2 um diameter.

TABLE 1 B1 % AE1 60 P1 40 Mooney Viscosity ML1 + 4, 100 C. 62B1 was then further blended with EVA1 at approximately 40° C. on a rollmill to produce blends B2-B4, as shown in Table 2.

TABLE 2 Blend B2 B3 B4 phr phr phr B1 107.1 62.5 27.8 EVA1 35.7 62.583.3 Mooney Viscosity ML1 + 4, 100 C. 45 34 27 Composition in weight %EVA1 25 50 75 AE1 45 30 15 P1 30 20 10

The formulations and properties of curable heat resistant ethylene vinylacetate compositions E1-E6 and comparative curable ethylene vinylacetate compositions CE1-CE5 are shown in Table 3. The curablecompositions were prepared by charging the ingredients as shown to aBrabender® mixing bowl fitted with cam rotors, operating at 50 rpm. Thebowl set temperature was 50° C., and the mixing time was three minutes.The batch temperatures did not exceed 100° C. After removing thecompounds from the mixing bowl, they were sheeted on a cold roll mill,and preforms were stamped out for molding plaques, compression setbuttons, and for measuring cure response.

Results in Table 3 show that all the curable compounds exhibit a goodcure response. Compounds E1, E2, and E3 do not contain carbon black, yetexhibit much greater tensile strength and Shore A hardness after presscure than the comparative composition CE1, which also does not containcarbon black. After heat aging for one week at 190° C., all theinventive compositions have tensile elongation to break greater than100% and very slight changes in Shore A hardness (less than 5 points)wherein comparative compositions exhibit less than 20% elongation tobreak and Shore A hardness increases of at least 18 points.

TABLE 3 E1 E2 E3 E4 E5 E6 CE1 CE2 CE3 CE4 CE5 phr phr phr phr phr phrphr phr phr phr phr B2 142.9 142.9 B3 125.0 125.0 B4 111.1 111.1 EVA1100 100 100 100 100 Peroxide 5 5 5 5 5 5 5 5 5 5 5 Coagent 2 2 2 2 2 2 22 2 2 2 Antioxidant 1 1 1 1 1 1 1 1 1 1 1 Carbon 9 18 27 9 18 27 36black Weight percent of EVA1, AE1, and P1 based on the total polymercontent EVA1 (%) 25 50 75 25 50 75 100 100 100 100 100 AE1 (%) 45 30 1545 30 15 0 0 0 0 0 P1 (%) 30 20 10 30 20 10 0 0 0 0 0 Cure Response ML(dN-m) 0.4 0.3 0.3 0.5 0.3 0.3 0.2 0.2 0.2 0.3 0.5 MH (dN-m) 12.4 10.18.2 13.9 12.4 12 7.4 7.9 9 11.5 14.3 MH − ML 12.0 9.8 8.0 13.4 12.1 11.77.2 7.7 8.8 11.2 13.9 (dN-m) Tensile properties and Shore A hardnessafter press cure Shore A 57 50 44 61 61 61 40 46 50 58 62 Tb (MPa) 12.610 6.8 17.9 16.1 17.6 1.7 5.2 12.5 15.2 16 Eb (%) 225 240 270 235 230245 200 240 260 245 205 Tensile properties and Shore A hardness afterpress cure followed by one week hot air aging at 190 C. Shore A 54 45 4257 60 63 79 65 75 78 80 Tb (MPa) 10.7 7.8 4.8 11.6 11.7 8.8 * 5.2 5.3 74.5 Eb (%) 230 240 235 190 180 135 * 5 15 20 15 change in * too brittleto test Sh A (pts) −3 −5 −2 −4 −1 2 39 19 25 20 18 Tb (%) −15 −22 −29−35 −27 −50 −100 0 −58 −54 −72 Eb (%) 2 0 −13 −19 −22 −45 −100 −98 −94−92 −93 Compression set, 70 hrs at 150 C. (%) 28 21 16 36 31 33 16 17 1924 16

Example 2

Blend B5 comprises polyacrylate AE1 and polyamide P2 as shown in Table4, and is produced according to the method of blend B1 in Example 1.Transmission electron micrographs of blend B5 indicate that thepolyacrylate elastomer is the continuous phase in the blend, and thepolyamide is dispersed in roughly spherical domains of approximately 2to 5 um diameter.

TABLE 4 B5 % AE1 55 P2 45 Mooney Viscosity ML1 + 4, 100 C. 69

B5 was further blended with EVA2 on a roll mill at approximately 40° C.to produce blends B6-B10 as shown in Table 5, ranging in polyamidecontent from 10 wt % to 0.2 wt %.

TABLE 5 Blend B6 B7 B8 B9 B10 phr phr phr phr phr EVA2 88.61 94.67 97.9599.5 99.8 B5 25.32 11.83 4.56 1.12 0.45 Mooney Viscosity ML1 + 4, 100 C.20 18 17 16 16 Composition in weight % EVA2 77.78 88.89 95.55 98.8999.55 AE1 12.22 6.11 2.45 0.61 0.25 P2 10 5 2 0.5 0.2

Blends B6-B10 were further compounded to produce curable compoundsE7-E9, CE6, and CE7 as shown in Table 6, using a Brabender® mixing bowlas described in Example 1.

A control compound (CE8) using EVA2 as the sole polymer component wasalso produced via the Brabender mixing bowl procedure as described inExample 1. Results in Table 6 show that all the compounds exhibit astrong cure response, and similar Shore A hardness and tensileproperties after press cure. After hot air aging for two weeks at 175°C., however, the inventive compounds comprising at least 1% polyamideand 1% polyacrylate elastomer exhibit only a 3 point increase in Shore Ahardness, compared with 10 points or more for the comparative examples.In addition, after heat aging the inventive compositions have more thanthree times greater tensile elongation to break than the comparativeexamples.

TABLE 6 E7 E8 E9 CE6 CE7 CE8 Compound phr phr phr phr phr phr B6 113.93B7 106.5 B8 102.51 B9 100.62 B10 100.25 EVA2 100 Coagent 2 2 2 2 2 2Peroxide 5 5 5 5 5 5 Antioxidant 1 1 1 1 1 1 Carbon black 30 30 30 30 3030 Cure Response ML (dN-m) 0.3 0.3 0.3 0.3 0.3 0.3 MH (dN-m) 10.5 9.59.3 9 9.1 9 MH − ML (dN- 10.2 9.2 9 8.7 8.8 8.7 m) Tensile propertiesand Shore A hardness after press cure Shore A 60 61 61 59 60 59 Tb (MPa)13.6 13.9 12.8 12.3 12.2 12.2 Eb (%) 210 240 235 205 230 210 Tensileproperties and Shore A hardness after press cure and two weeks hot airaging at 175° C. Shore A 63 58 64 69 76 79 Tb (MPa) 10.1 7.2 4.5 3.3 4.45.3 Eb (%) 170 125 75 20 20 20 change in Sh A (pts) 3 −3 3 10 16 20 Tb(%) −26 −48 −65 −73 −64 −57 Eb (%) −19 −48 −68 −90 −91 −90

Example 3

Blends B11 and B12 were produced by charging EVA2, AE1, and P1 in theproportions shown in Table 7 to a Brabender® mixing bowl. The bowl wasfitted with roller blades, and preheated to 240° C. The three polymerswere mixed at a rotor speed of 100 rpm. As the temperature of the batchachieved 220° C. (the melting peak temperature of P1), a timer wasstarted and air cooling initiated to maintain a batch temperature ofabout 240° C. After 3 minutes of mixing, the blends were discharged fromthe bowl, and cooled to room temperature before further processing.

TABLE 7 Blend B11 B12 % % EVA2 67 60 AE1 3 10 P1 30 30 Mooney ViscosityML1 + 4, 100 C. 36 36

Curable compositions E10 and E11 were produced according to theformulations in Table 8 by roll mill mixing at a temperature of about40° C. These compositions exhibit strong cure response, and excellentphysical properties after press cure followed by a post cure of 30minutes at 175° C., as well as after hot air aging of one week at 190°C.

TABLE 8 Compound E10 E11 phr phr B11 142.9 B12 142.9 Coagent 2 2Peroxide 5 5 Antioxidant 1 1 Cure Response ML (dN-m) 0.4 0.4 MH (dN-m)11.8 11.4 MH-ML (dN-m) 11.4 11 Tensile properties and Shore A hardnessafter press cure 10 min/ 175° C. and post cure 30 minutes/175° C. ShoreA 60 60 Tb (MPa) 13.5 13.4 Eb (%) 200 215 Tensile properties and Shore Ahardness after press cure, post cure and 1 week hot air aging at 190° C.Shore A 56 57 Tb (MPa) 9.1 9.4 Eb (%) 180 185

1. A blend composition of ethylene vinyl acetate copolymer, peroxidecurable polyacrylate elastomer, and polyamide, said blend compositionconsisting essentially of (A) from about 10 wt % to about 98 wt % of anethylene vinyl acetate copolymer component said ethylene copolymercomponent comprising one or more ethylene vinyl acetate copolymers of atleast 40% by weight copolymerized vinyl acetate monomer units; and (B)from about 1 wt % to about 50 wt % of a one or more of peroxide curablepolyacrylate elastomer component comprising copolymerized units of alkylacrylate, and at least 0.03 mol % of an amine or acid reactive monomerselected from the group consisting of unsaturated carboxylic acids,anhydrides of unsaturated carboxylic acids, and unsaturated epoxides;and (C) from about 1 wt % to about 60 wt % of a polyamide componentcomprising one or more polyamides having a melting peak temperature ofat least 160° C., wherein said blend composition has a Mooney viscosity(ML 1+4, 100° C.) determined according to ASTM D1646 of 5 to 200; andwherein each of the weight percentages of the ethylene vinyl acetatecopolymer, polyacrylate elastomer, and polyamide components are based onthe combined weight of the ethylene vinyl acetate copolymers,polyacrylate elastomers, and polyamides in the blend composition. 2.(canceled)
 3. The composition of claim 1 wherein the polyamide is nylon6 or nylon 6/6.
 4. The composition of claim 1 wherein the polyamide hasan inherent viscosity greater than 0.9 dL/g.
 5. The composition of claim1 wherein the polyamide is present in the form of particles having anaspect ratio of less than 10 to
 1. 6. (canceled)
 7. The composition ofclaim 1 wherein the polyacrylate elastomer comprises at least 50 mol %ethylene.
 8. The composition of claim 1, said composition comprisingfrom about 50 wt % to about 90 wt % of the ethyl vinyl acetate copolymercomponent, 5 wt % to 20 wt % of the polyacrylate elastomer component,and 5 wt % to 30 wt % of the polyamide component.
 9. The composition ofclaim 1, wherein upon addition of a curative said composition exhibitsan increase in torque MH-ML of at least 2.5 dN-m as measured per ASTMD5289-07a operating at 0.5° arc, and test conditions of 177° C. for 24minutes.
 10. A process for production of the composition of claim 1,said process comprising the steps (A) providing (i); (ii); and (iii);(B) mixing (i), (ii), and (iii) together at a temperature above themelting peak temperatures of the one or more polyamides to disperse theone or more polyamides within the blend of one or more ethylene vinylacetate copolymers and polyacrylate elastomers, such that one or moreethylene vinyl acetate copolymer comprise 10 wt % to 98 wt %, the one ormore peroxide curable polyacylate elastomers comprise 1 wt % to 50 wt %,and the one or more polyamides comprise 1 wt % to 60 wt % of the blendbased on the total weight of ethylene vinyl acetate copolymers,polyacrylate elastomers, and polyamides present, to produce a mixture;and (C) cooling the mixture to a temperature below the crystallizationpeak temperatures of the one or more polyamides, thereby forming a blendcomposition having a Mooney viscosity (ML 1+4, 100° C.) of 5 to 200, asdetermined according to ASTM D1646.
 11. A process for preparing thecomposition of claim 1, said process comprising the steps: (A)providing: (i) one or more curable polyacrylate elastomers comprisingcopolymerized units of alkyl acrylate, and at least 0.03 mol % of anamine or acid reactive monomer selected from the group consisting ofunsaturated carboxylic acids, anhydrides of unsaturated carboxylicacids, and unsaturated epoxides; and (ii) one or more polyamides havinga melting peak temperature of at least 160° C.; and (B) mixing the oneor more curable polyacrylate elastomers and one or more polyamides attemperature above the melting peak temperatures of the one or morepolyamides to disperse the one or more polyamides within the one or morepolyacrylate elastomers; to provide a mixture and (C) cooling themixture of part B to a temperature below the peak crystallizationtemperatures of the one or more polyamides to produce an intermediateblend composition having a Mooney viscosity (ML 1+4, 100° C.) less than200 as determined according to ASTM D1646; and (D) providing one or moreethylene vinyl acetate copolymers comprising at least 40% by weightvinyl acetate monomer; and (E) mixing the intermediate blend compositionof step (C) with the one or more ethylene vinyl acetate copolymers ofstep (D) to provide a blend composition comprising 10 wt % to 98 wt %ethylene vinyl acetate copolymer, 1 wt % to 50 wt % curable polyacylateelastomer, and 1 wt % to 60 wt % polyamide, each being based on thecombined weight of the ethylene vinyl acetate copolymers, polyacrylateelastomers, and polyamides in the blend composition.
 12. The process ofclaim 10, wherein said blend composition comprises 50 wt % to 90 wt % ofthe ethyl vinyl acetate copolymer component; 5 wt % to 20 wt % of thepolyacrylate elastomer component; and 5 wt % to 30 wt % of the polyamidecomponent
 13. The process of claim 10 wherein the polyamide is nylon 6or nylon 6/6.
 14. The process of claim 10 wherein the polyamide has amelting peak temperature greater than 200° C. and less than 270° C. 15.The process of claim 10, said process further comprising, adding one ormore antioxidant in an amount of from 0.5 to 5 phr.
 16. The process ofclaim 10, wherein upon addition of a curative the composition has a cureresponse MH-ML of at least 2.5 dN-m as determined according to ASTMD5289-07a, operating at 0.5° arc and test conditions of 177° C. for 24minutes.
 17. (canceled)
 18. (canceled)
 19. The process of claim 10 forforming an article selected from the group consisting of wire jacketing,cable jacketing, molded or extruded tubing or hose, or molded boots,belts, grommets, seals and gaskets, said process further comprising thestep of forming the article.
 20. An article formed by the process ofclaim
 19. 21. The blend composition of claim 1, wherein the polyamidehas a melting peak temperature greater than 200° C. and less than 270°C.
 22. The blend composition of claim 1, further comprising one or moreantioxidants in an amount of from 0.5 to 5 phr.
 23. An articlecomprising the blend composition of claim
 1. 24. The process of claim 11for forming an article selected from the group consisting of wirejacketing, cable jacketing, molded or extruded tubing or hose, or moldedboots, belts, grommets, seals and gaskets, said process furthercomprising the step of forming the article.
 25. An article formed by theprocess of claim 24.